Carburetor



June 20, 1939 J [BRANDON 2,163,139

' CARBURETOR Filed May 22, 1937 3 Sheets-Sheet 1 i7 5 7* H: i .1 3 31 1* 6 3' r 3 I &\ 21 134...?

.41, BY 42 Y Z ATTORNEY.

INVENTOR.

June 20, 1939. J. BRANDON CARBURETOR 3 Sheets-Sheet 2 Filed May 22, '1937 INVENTOIFQ.

ATTORNEY.

June 20, 1939. J. 1. BRANDON CARBURETOR File d May 22, 1957 3 Sheets-Sheet 3 filNVE'NTOR. BY $0M M ATTORNEY.

lit

Patented June 20, 1939 UNITED STATES PATENT OFFICE 15 Claims.

My invention relates to carburetors, more particularly to down-draft carburetors for vehicle engines, A primary object is to provide a carburetor which produces an extremely complete and finely dispersed atomization of the fuel and air mixture so that no vapor or liquid particles remain and condensing out'or reliquifying of the fuel in the manifold and cylinders of the engine is minimized.

A further object is to provide a carburetor wherein the fuel and air mixture passes through a series of Venturi tubes of increasing diameter adapted to progressively increase the amount of air brought into contact with thefuel charge until the entire air stream is thoroughly mixed.

A further object is to provide a carburetor which is particularly designed for the modern high speed engine and the correspondingly high air velocity required in the carburetor thereof by insuring complete dispersement of the fuel within the extremely short time interval available between introduction of the fuel charge and passage of the fuel and air mixture into the manifold.

A further object is to provide a carburetor which incorporates a novel rotating venturi driven by the air stream itself and having driving vanes so arranged as to form fuel entrapping ducts adapted to collect imperfectly atomized fuel 1 and re-discharge it in finely divided form, into the air screen, 1

A still further object is to provide a carburetor which incorporates a novelly arranged expanding Venturi through which the entire air stream must pass and which tends to increase in diameter as the demands of the vehicle engine increases, thereby tending to increase the capacity of the carburetor with increased demand.

A still further object is to provide a carburetor having a novelly arranged body structure wherein an annular float chamber surrounds the air passage to form a compact unit facilitating mountingand incorporation of the various adjustment and accessory elements in readily 'ac-' I cessible locations, whereby the carburetor may be readily and quickly adjusted and serviced.

A still further object is to provide a carburetor thereof and the float .levelofgthe float chamber 1 a carburetor quantity when the throttle is opened less rapidly; thus eifecting a saving of fuel particularly at higher speeds by eliminating introduction of an overcharge of fuel when reopening the throttle after a momentary release and before engine speed has dropped appreciably.

With the foregoing and other objects in view as may appear hereinafter, reference is made to the accompanying drawings, in which:

Figure 1 is a longitudinal sectional view of my carburetor with the intake and manifold ducts -shown fragmentarily, the section being taken substantially through I! of Figure 1 and parts shown in elevation to facilitate the illustration.

Figure 2 is an enlarged fragmentary sectional view taken in the same plane as Figure 1 and illustrating particularly the construction of one of the running jets.

Figure 3 is a fragmentaryradial sectional view taken through 33 of Figure 7 and illustrating one of the float spring adjustment units.

Figure 4 is another fragmentary radial sectional view taken through 44 of Figure 7 showing the needle valve, compensating piston structure and accelerating jet,

Figure 5 is an enlarged sectional view taken through 5 -5 of Figure 4 showing the accelerator and compensating piston structure.

Figure 6 is a transverse sectional view thereof taken through 66 of Figure 4.-

Figure 7 is a plan view of the carburetor taken from the line l'l of Figure 1 at a slightly smaller scale and with the carburetor intake shown in section.

Figure 8 is a transverse sectional View taken through 8 8 of Figure 1 with the rotatingvenuri shown in elevation. I

Figure 9 is an elevational view of the iower or expanding venturi taken approximately along the line 99 of Figure 1 with a portion thereof being, broken away and in section.

The principal elements of my carburetor, are

incorporated in a main housing I. Thisihous ing' isvgenerally tubular in form with a central, vertically'extending air passage-,2 therethrough. ,Atj

. its upper portion the passage Zis surroundedjby an annular float chamber 3,.wh'ich'may constitute anfinteg'ra'l' part of the housingfl. The fioat y I chamber-is open at its upper side and is flanged around its inner and outer peripheriesto receive 1 I an annular cover' i. The cover dmay form an integral part or skirt atthe'lowerl'end of an air intake tube 5 which registers with" thefair."

passage 2.

The air passage 2 receives a primary or fixed venturi 6 which occupies approximately half the diameter of the air passage and which is positioned with its upper or throat end slightly above the normal fuel level within the float chamber as will be brought out hereinafter. The primary venturi 6 is supported by radial webs I which in turn are secured to the-housing I in any suitable manner such as by a suspension ring 'IA- clamped betweenthe housing I and air intake tube 5,

The air passage 2, as such, terminates at a point slightly above the lower end of the primary venturi 6. Below this point thehousing I is enlarged to form a bearing sleeve 8 which receives a pair of ball bearing rings 9. These, in turn journal a cylindrical shell ID having an internal diameter equal to and in registry with the air passage 2. Centered within the shell [0 by means of radiating webs H and I! at its upper and lower ends is a rotating or secondary venturi l3.

The secondary venturi is larger than, and, its

upper end telescopes over'the lower end of the primary venturi 6. Clearance is provided between the two venturisand adjacent its lower end the primary venturi is provided with a ring of inwardly and downwardly directed ports l4 which feed from the outside of the primary into the interior of the secondary venturi.

Both venturis have outer peripheries of uniform diameter; and venturi shaped passes therethrough. That of the upper or primary venturi is smooth, while the passage of the secondary venturi is provided with a plurality of helical ducts I5. Each duct l5 converges from its upper to its lower end to form downwardly and anguwith a flange I 8 which is adapted to be secured to a flange IQ of a discharge tube 20. Preferably,

however, there is interposed between the flanges a thick gasket 2| of heat insulating material.

- The discharge tube 20, shown fragmentary in the' drawings, communicates with or forms part of the intake manifold, notshown. The discharge tube 23 is split longitudinally, or otherwise dl-,-.

vlded to permit insertiOn of' a split or tertiary venturi 22. This venturi is in the form of two or more axially split complementary segments 23 having overlapping margins 24. Each segment is provided near its upper and lower ends with radial ribs 25 which flts in channelsji provided in the wall of the discharging tube. The ribs and their channels have suflicient arc'uate extent to restrain the segments against tilting out of Each segment is backed by a spring 21 which extends outwardly through an opening. provided in the discharge tube 20 and thetension of which is adjustable by a set screw 28. The tertiary venturi is materially larger than the secondary venturi and the shell ll overhangs its upper end The float chamber 3 receives an annular-float, 3l. Said float is yieldably restrained in position by three springs "32. The lower end of each spring, as shown in Figure 3, fits in a cup 33 provided on the upper side of the float 3|. Each spring extends upwardly through a. threaded opening provided in the cover 4 and into an adjustment screw 34 which is adapted to be locked in position by a nut 35. One of the springs 32 is materially weaker than the others and ad-.

jacent this spring, as shown in Figure 4, is positioned a needle valve 36. The lower end of the eral springs as well as the needle valve adjusted" until the; desired liquid level is reached as determined by inspection through the ports. Very little movement of the float is required OOIISG', quently stop lugs 40 may extend upwardly from the bottom of the float chamber to limit movement of the float.

It is to be understood that the springs 32 may be loose in the adjusting screws 34, in order 'that the float may rise and fall without any resistance by thesprings, except when the float rises to a position in which the compressionof the springs '32 begins.

The springs 32 are preferably fastened in the cups 33. Thus lateral deflection of the float is resisted by the springs. I

At diametrically opposite sides, the housing is provided with upwardly and inwardly sloping thickened portions 4| which are provided with bores 42 constricted at their inner ends to form shoulders. A running jet assembly 43 is associated with each bore 42 and comprises: a bleeder tube 44 having a flanged end adapted to be sealed Each bleeder tube 44 receives a fuel tube 41 also having a flanged end and held concentrically ,by reason thereof. The inner end of the fuel 'tube 4I 'terminates short of the venturi constriction and adjacent this end is provided with external helical flutes 48 to cause rotation of air entering the ports 46, This serves to partially break up the fuel entering through the tubes 41. The upper ends of the running jets are preferably disposed at the throat of 'the primary venturi -and the liquid level in the float chamber is adjusted so as to be slightly below the discharge ends of the running jets.

The tubes 44 and 41 are held in place by a meter plug 49 having a meter oriflce 53 therein. Each-bore 42 is intersected laterally by a passage 5| communicating with the float chamber 3. The outer ends of the bores 42 are closed by plugs 42a. In addition to the, running jet assemblies, suitable idler jet'or jets, not shown are of course contemplated; these, however, may be conventional'in design. Further, an accelerator jet I2 may be provided, this may take the form of the running jets andlikewise discharge into the primaryventurl. The accelerator jet" is supplied from a special accelerator pump I.

The accelerator pump]! is'incorporated in a -3 pair of cylinders l2 and 33 which may form an .fioat chamber 3. Each cylinder is closed at its lower end and communicates, by means of a passage controlled by a suitable check valve 64, with the bottom of the float chamber 3. Also the lower or closed end of each cylinder is provided with a discharge ,check valve 65 controlling a cross passage 66 which intersects a supply passage I61 leading to the accelerator jet 52, all of which is shown best in Figures 4, 5, and 6.

The cover 4 of the float chamber may incorporate an upwardly directed dome 61 embracing and closing the upper ends of the cylinders 62 and 63. Above cylinder 62 the dome 61 is provided with a. guide opening which receives a plunger stem 68a. The stem is secured. to a main accelerator plunger 68 of any suitable construction. .The .plunger 68 may carry a tip or prong engageable with the corresponding discharge valve 65 to hold the same open when the plunger is in its lowermost position.

The cylinder 63, which may be termed the delayed action cylinder, receives a central rod 69 secured in the bottom of the cylinder and in the dome 61. At its lowermost end, the rod is provided with ports which afford communication with corresponding discharge valve 65. Slidably mounted on the rod 69 is a delayed action plunger 1|. Said plunger is provided with a pair of check valves'12, which are so designed that upon rapid downward movement, they close preventing by-passing of fluid through the plunger, whereas, upon relatively slow movement of the plunger, fail to close and thereby bypass the fluid.

Springs '13 and 14 are mounted around the rod 69, while slidably interposed between the upper spring 14 and the upper end of the rod is a yoke which is secured to the stem 68a. Liquid entrapped above the plunger 12 discharges back into the fioat'chamber 3 through a port 16, shown in Figure 4, provided at the upper end of the cylinder 63.

Operation of my carburetor is as follows:

In normal operation, flow of air through the primary venturi 6 creates suflicient suction to draw both fuel and air from the running jets 42. This partially mixed fuel and air is further atomized as it passes through the primary venturi. For the reason that velocity through any tube is fastest in the center and diminishes toward the walls, the heavier and less mixed particles of fuel tend to flow toward the walls of the primary venturi. Here they are acted upon by air entering the ports I4. The remaining larger particles of fuel tend to enter the ducts l5 of the secondary venturiJ 3, and together with air entering between the primary and secondary venturis tend to rotate the secondary venturi at a high velocity. This further atomizes the fuel. Any particles that may have entered theducts are urged by centrifugal force out the bottom or nozzles I6 and discharge in thoroughly atomized form into the tertiary venturi 22'. The fuel and air upon entering the tertiary venturi is thoroughly mixed, and while the tertiary venturi aids in further atomization its principle function is to expand as the demands of the engine increase so that a greater volume of air and fuel may be admitted to the engine. This is done automatically by compression of the springs 21 as the pressure within the tertiary venturi increases. Only slight expansion is required to effect advantageous results.

The accelerator jet 52 functions to supply an erator jet 52.

extra quantity of fuel when the engine is picking up speed. While piston and cylinder means have been employed heretofore in order to supply the extra fuel, difiiculty has been encountered in the fact that each depression of the accelerator pedal measured a fixed quantity of fuel. Actually, however, there is very little need for the accelerator pump action when the engine is accelerated comparatively slowly. With the dual accelerator pump arrangement described hereinbefore, both of these conditions may be met.

Thus, when accelerating rapidly, and the plungers 68 and 1| are moved rapidly, fuel from both cylinders 62 and 63 are delivered to the accel- But, when the engine is accelerated less rapidly, the delayed action plunger 1| moves less rapidly, valves 12 therein fail to close, and only the fuel from the cylinder 62 is delivered to the accelerator jet. The springs 13 and 14 and the mass of the plunger 1| are so proportioned that with the rapid movement of the yoke 15, the upper spring 14 tends to snap the plunger down and insure closing of the valve 12, while with slower movement insures a more gradual movement of the plunger. In either case there is a certain lagging of the plunger 1| which tends to prolong and more effectively discharge the extra fuel through the accelerator jet.

Though I have shown and described a particular embodiment of my invention, I do not wish to be limited thereto, but desire to include in the scope of my invention the constructions, combinations and arrangements substantially as set forth in the accompanying claims.-

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A carburetor comprising body means defining an air passage; a Venturi element mounted therein; means for supplying fuel to said Venturi element; a second venturi adapted to receive the discharge from said Venturi element; means freely journalling said second, venturi; and a plurality of helical ducts lining the second venturi responsive to the flow of fuel and air therethrough to impart rotation to said second venturi, said ducts including fuel entrapping and discharge nozzles adapted to collect entrained fuel particles and re-spray the same into the air stream.

-2. In a carburetor comprising an air passage defining structure, a fuel drawing Venturi element positioned in but spaced from the wallsof the air passage, and means for supply fuel to said Venturi element, of: a secondary venturi also mounted in said air passage, said secondary venturi being larger than and partially telescoping over said Venturi element to receive the fuel and air discharge therefrom; means freely journalling said secondary venturi; and means responsive to air flow through said passage for rotating said secondary venturi. F

3. A carburetor comprising an .air passage defining structure; a plurality of Venturi elements of progressively increasing size mounted therein, the larger defining the effective area of said air passage; means for varying the area of said larger Venturi element; a journal for an intermediate Venturi element; helical vanes incorporated with said intermediate Venturi element for imparting rotation thereto; ducts associated with said vanes adapted to receive entrained fuel particles; discharge nozzles for said ducts; and means for supplying fuel to said smaller Venturi element for subsequent discharge into said intermediate and larger Venturi elements.

4. A carburetor comprising a body structure defining a central air passage, and annular float chamber around the intake end of said air passage; 9. fixed venturi mounted within the air passage at its intake end and spaced from the side walls thereof, said fixed venturi having a throat disposed above the normal fuel level of said float chamber; fuel jets communicating between said float chamber and said throat whereby flow of air therethrough draws fuel into said fixed venturi; a rotatable venturijournaled at the discharge end of said fixed venturi to re- 'ceive fuel and air therefrom; and means responsive to the flow of air for imparting rotation to said rotatable venturi.

-5.' A carburetor comprising a body structure defining a central air passage, and an annular float chamber around the intake end thereof; a fixed venturi mounted within the airpassage at its intake end and having a throat disposed above the normal fuel level of said float chamber; radially disposed fuel jets communicating between said float chamber and throat whereby flow of air therethrough draws fuel from said float chamber; a rotatable venturi journaled at the discharge end of said fixed venturi and larger than the same for receiving air from said passage as well as the discharge from said fixed venturi; helical vanes lining said rotatable venturi for imparting rotation thereto; fuel parare (float chamber and said throat disposed above the normal fuel level of said float chamber; fuel jets communicating between said hereby flow of air therethrough draws fuel into said fixed venturi; a rotatable venturijournaled at the discharge end of said fixed venturi to receive fuel and air therefrom; and an expansible' venturi disposed at the discharge end of said rotatable venturi and defining the effective area of said air passage.

9. A carburetor comprising a body structure defining a central air passage, and an annular float chamber around the intake end thereof; a fixed venturi mounted within the air passage at its intake end and having a throat disposed above 1 the normal fuel level of said float chamber; ra-

, ticle collecting ducts associated with said vanes;

dially disposed fuel jets communicating between --said float chamber and throat whereby flow of air therethrough draws fuel' from said float chamber; a rotatable venturi journaled at the discharge end of said fixed venturi and larger.

than the same for receiving air from said passage as well as the discharge from said fixed venturi; helical vanes lining said rotatable venturi for imparting rotation thereto; fuel parand an expansible venturi at the discharge end of said rotatable venturi defining the effective area of said air passage; yieldable means tending, to restrain said expansible venturi to its smaller size, said expansible venturi being responsive to the flow of air therethrough to expand in opposition to said yieldable means as the quantity of air flowing therethrough increases.

8. In a carburetor having a main air passage,

' lapping, complementary segments, the overlapfuel receiving and atomizing means therein, and means for supplying fuel thereto; an expansible venturi at the discharge end of said air passage defining the effective area thereof, the outer circumference of said expansible venturi being entirely movable, complementary segments movable inward and outward to contrabt and expand the entire inner circumference of the Yenturi throat, and separate yieldable means tending to urge said segments inwardly to reduce the area 1 of said expansible venturi, said venturi being responsive to increase in air flow therethrough to expand against said yieldable means. i

9. A carburetor comprising a body structure defining an air passage, a float chamber in as- 1 sociation therewith, a venturi in the air passage, an accelerator fuel pump including a cylinder and a piston in the cylinder, a connection between the cylinder and the float chamber, a jet connected with the cylinder and discharging into 1 the venturi, valves controlling the ingress and egress of fluid to d from said cylinder, actuating means for the pump, spring means to yieldingly communicate movements of the actuating means to the piston, and fuel bleeding means re- 5 sponsive to the operation speed of the piston whereby the capacity thereof is diminished with decrease in operating speed.

10. A carburetor comprising a .body structure defining an air passage, a float chamber in assog ciation therewith, a venturi in the air passage, an accelerator fuel pump including a cylinder and a piston in the cylinder, a connection between the cylinder and the float chamber, a jet connected with the cylinder and discharging into 1 the venturi, valves controlling the ingress and egress of fluid to and from said cylinder, spring means to yieldingly resist movements of the piston in opposite directions, and fuel bleeding means responsive to the operation speed of the 4 piston whereby the capacity thereof is diminished with decrease in operating speed.

11. A carburetor comprising a body structure defining an air passage, a float chamber in association therewith, a. venturi in the air passage, an accelerator fuel pump including two cylinders and pistons in the cylinders respectively, a connection between the cylinders and the float chamber, a jet connected with the cylinders and discharging into the venturi, valves controlling the ingress and egress of fluid to and from said cylinders, oneof said pistons being fluid tight,

and the other piston having a fluid bleeding valve to by-pass fuel with respect to the piston in inverse ratio to the operating speed thereof.

12. A carburetor comprising a body structure defining an air passage, 9. fioat chamber in association therewith, a venturi in the passage, and a jet comprising spaced tubes, one within the other, the outer tube having an air inlet port and hava ing a Venturi tip discharging into said venturi, the inner tube connecting with the float chamher and discharging into the Venturi tip, the jet having helical meanstending to stir the fluid in the jet prior to the discharge of said fluid into 1 the first mentioned venturi.

13. In a carburetor having an air passage, means for supplying fuel thereto, and an expansible venturi in the passage, comprising overping portions being slidable one onthe other, to change the effective area of the throat of the venturi, the segments being responsive to move to positions enlarging said throat, upon increase 7 of the flow of fluid through the venturi and spring means tending to move the segments toward each other.

14. In a carburetor having an air passage, a

venturi in the passage, means for supplying fuel thereto; and an expansible venturi connected to a receive air and fuel mixed in the first-mentioned venturi, the expansible venturi comprising complementary segments responsive to move to positions enlarging said throat, upon increase of the flow of fluid through the venturi and spring means tending to move the segments toward each other.

15. A carburetor comprising body means deventuri against the air pressure in the passage. 10

JOSEPH I. BRANDON. 

